A supermoon, technically called a “perigee moon,” occurs when the moon is full within 24 hours of it being at its closest point to the Earth in its orbit. August’s moon will be the biggest and brightest because it occurs just 26 minutes after the moon will be at its closest point to the Earth. A supermoon also appeared on July 12 and the next will take place on Sept. 9, but neither will be as bright as this weekend’s moon.

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“The three full moons in a row are close to the moon’s perigee and it just so happens that the August one is almost exactly full and at perigee,” explained Colin Haig, vice-president of the Royal Astronomical Society of Canada. But Mr. Haig said the difference between a supermoon and a regular full moon is marginal and almost impossible to notice with the naked eye.

“It’s gotten a bit exaggerated, maybe even a little silly,” Mr. Haig said of the supermoon moniker.

To really notice the difference, he said it’s better to take photos with a high-quality lens to compare the size and brightness with a regular full moon.

Supermoons occur approximately every 13 months and 18 days, but the full moon won’t be as close to the Earth again in 2014 as it will be this weekend.

But astronomy buffs hoping to catch sight of another spectacle in the sky may be disappointed by the moon stealing the spotlight.

The Perseid meteor shower is one of the brightest showers that lights up the night sky with shooting stars once a year as debris from the comet Swift-Tuttle burns up in Earth’s atmosphere. The darker the night sky, the easier the meteors are to spot, but the shower will peak just two days after the supermoon. The still extra-bright moon will be in the sky most of the night, making it harder to catch a glimpse of the shooting stars.

Mr. Haig said if all the other factors are right, the moon shouldn't pose too much of a problem. If the weather is clear where you are and there aren’t any other lights, you should be able to spot a few meteors.

“Many of them are going to be quite faint and you may be blessed with a few really bright, fast-moving ones that are easy to spot, but the darker the skies, the better the odds.”

Luckily, Mr. Haig says the meteors will start to appear Friday night and will continue into next week as the moon's
brightness wanes, so it should be easier to spot the meteors before and after the supermoon’s big debut.